So firstly all the 4 different machine designs are +80mm or more longer on the X axis, so I can fit a Dual+ extruder (and my new X carriage, see below).

I decided to get different sets of Aluminium extrusions cut for four different sized machines. - I need better names but -

1) - The normal model is just 80mm bigger on X - this would be more than adequate for most situations and is very similar to a Prusa Mendel in size and shape.

2) - The mini model is more like a Huxley, it's going to be a single extruder (Bowden Fed) and designed to be very strong and transportable (150mm x 150mm bed size)

3) - The Big model is what I have built up first, this is going to be for my hack and test machine, with the ability to print upto 305mm x 305mm bed size.

Big Max and Mini Max

4) - The Massive one is a little silly really, and I'm not sure I'll build it up, and certainly not with 8MM smooth bars.

The Frame around the Mini Max above is the lower section of the Massive model, build area is about 450mm x 450mm, not sure what the Z would be, around 320mm+ I expect.

I'm using Bosch-Rexroth 20mm Aluminium Extrusions from KJN here in the UK - They are a really excellent company to deal with, and offer great pricing and cut to length service as standard! - Do take a look.

This was my stack of Extrusions - 2.7M long package on a wood base to keep it all straight.

You will need to Tap the ends of almost all the frame sections, and with Bosch Rexroth you need an M6 Tap - the Mitsumi Extrusions listed on the MendelMax home page use M5 - so check before you buy the bolts!

I contemplated a 20mm Alu frame for the Y axis, opted for MDF just to get it running.

Heated build Bed.

I considered designing a bigger PCB heated bed, and also an aluminium one, but as this was a test to see if I would need, and actually also use a bigger build area. I firstly decided to use a standard V2 Prusa PCB and a standard copper clad PCB to spread the heat over a wider area.

I'm using the 'spare' hole in the middle of the Prusa V2 PCB to clamp using a countersunk M3 screw into my copper clad PCB board.

Simply wired up and clamped with M3 screws in the corners and middle, thermistor is on the copper clad board at the side. The middle screw is also acting as a cable strain relief.

I'm not a believer in measuring the temperature in the middle of a head bed, I always measure at the edge or corner.

Z Axis -

NOTE : - I'm still using M8 Stainless smooth rods on all the MendelMax machines, but if you are thinking about making a MAX (or any big machine) with a bigger build area than 300mm x 300mm then I really would recommend going to 10mm / 12mm, you will find 12mm costs less for the Bearings but the rods are quite a bit heavier, 16mm is overkill.

Back to the old style Z design (Clamp, rather than push-fit) - slight modifications including an adjustable Z- height screw/spring. Slightly, shorter, fatter and chunkier all around.

I always add Kapton tape to the X bar going into the Z ends, helps them grip in the plastic, I do this even if using push-fit Z ends.

I'm using Aluminium Flexible couplers on Max - these are really great if your Z axis is supported. They should not really be used on designs where the Z axis is hanging (Prusa and Huxley) or compressing (Printrbot and Wallace) without using some sort of support for the Z threaded rods.

I have started seeing a lot of people fitting these to designs that really need a solid coupling, for that I would always use Nopheads Motor coupler

On MendelMax the support for the Z rods are provided by Thrust bearings (shown above).

I'm also using M6 threaded rod for the Z axis over the more common M8, I find it gives better results and does not fight with the M8 Smooth rods for control over the X carriage placement in horizontal alignment when moving the X carriage vertically.

The original Z supports looked like this, and still used M8 Thrust bearings with a washer on top to allow for the smaller M6 threaded rod, quite a noisy arrangement, so they got changed to the below versions after first testing of the machine.

This is based on the Z axis mount design by AlephObjects my version of changes the Thrust bearing size so M6 Rods can be used and also fills up some holes in the AlephObjects version along with making it a little easier to print (mainly the vertical curve on the back - it now has a sharp bridge point).

Even with just two M4 bolts holding on my Greg's accessible extruder I still find it a pain to swap-out extruders so I decided to re-design the X carriage to allow a quick extruder change and also make it big enough for Dual extrusion and mounting other things -

I'm not yet experienced with OpenSCAD so I used Sketchup for this design, if anyone apart from me finds the idea useful it would be great to do it as a parametric OpenSCAD model, I can already see a need for a LM10UU version.

I'm getting to grips with Sketchup now, you can do quite a lot with it.

My aims for this design -
Horizontal X design compatible spacing with Mendel, Prusa Mendel and MendelMAX
Use Linear bearings (LM8UU) and make them very easy to fit.
Quick-fit and removal of Extruders (And other devices... more on that shortly)
Maximum space for extruder/hot-ends/heat-sinks between the smooth X bars
Allow dual or more extruder's to be fitted at once.
Allow for an easy extension of the X carriage (for future upgrades) - that needs some explanation, see below.
Printable on a Prusa, Huxley or TOM without support material.

This is my design for a 'Quick-Fit' clamp and expandable X-carriage -

It's printed vertically in two parts, without the need for support material - bolted together.

A key feature about the design is that you can extend it, even when it's fitted on the machine, you would unbolt the two halves and insert a printed spacer each side then bolt back together, allowing triple extruder's to fit or something bigger...

Hot end -
My current hot-ends of choice are J-Heads - I could do a whole post on how good they are. I do make a few changes before using them - Here is what I do to a normal MK-IV hot-end -

All of this is done for mounting, cooling, support of the PEEK at it's weakest point and to stop as much heat from rising up the PEEK as possible.

Take a standard M12 Linear Rail mount (£1.50) and drill out to 16mm or slightly under.

Widen the mounting holes (more than in this photo) and de-burr edges.

You then have the minimum amount of Aluminium for support and maximum cooling.

You could start with a M16mm rail mount, but they are much bigger overall and will be heavy.

You can drill more holes to allow better cooling.

Fit and tighten around the PEEK/Nozzle end this way around.

You can then fit 12/16mm M4 Nickel coated brass PCB stand-off's to the extruder body

Screw in Stainless steel M4 screws and washers, clamping the PEEK into the extruder nice and tight.

Optionally also fit a nut on the thread, to lock it on the stand-off.

After this fit your heating resistor (6R8 or 5R6) and thermistor and do remember to insulate the brass part with Ceramic rope/tape, glass rope/tape and/or Kapton.

For Printing in PLA I use a small 40mm directional fan blowing across the Aluminium rail block and across the fins in the PEEK, for Printing in ABS, don't use a fan.

New Heated Bed surface -
When building the big Max, I needed a glass bed, but wanting to keep down the weight I went looking for some 2mm glass, didn't have much luck and out of desperation I decided to try using a mirror, it was a good test size and easily came out of the nasty plastic frame. And it was only £1 from my trusty home shop.

If you try it, let me know, my results using mirror-glass have been really positive and interesting - a few observations -

The glass surface heats up fast and spreads heat very evenly over the surface, cool-down is quick but seems slower than just plain glass alone.

I hear less 'cracking' of the parts as they cool down.

For me PLA parts never seem to completely lift-off when cooled, don't ask me why this is, maybe thermal expansion, retraction is acting differently due the the reflective surface, but they stay a little stuck down - still very easy to remove with fingers, but all other glass surfaces I have used to date make the parts lift completely when cooled.

I needed to reduce my bed temperature from 60 degrees down to 45 degrees for PLA when using the mirror surface, if you don't do this it's like building on jelly, the PLA stays so very soft.

I think you could go lower than 45 degrees, I'll investigate at some point.

You need your first layer height set perfectly, (can be higher than normal) if not it seems to make more of a mess as the PLA is seems much softer for at least the first 3mm of building.

The mirror is also very handy for monitoring first layer bonding and looking at the underside of the X carriage.

I have just also started using mirror-glass with ABS (with PET tape on the surface) - I can reduce the bed Temperature to 85 degrees C and get no warp even on very large parts (120mm+ wide) I have tried with three different ABS types at the moment, but they were my worst for warping (Pink,Yellow and Blue).

2mm Mirror Glass with PET tape for printing ABS

I would be highly interested in any feedback on this topic - try it out if you can.

UPDATE - While I was typing this bit up, a post appeared from Theodleif on the RepRap Forum suggesting using a solution of sugar water painted onto a hot mirror-tile for printing ABS, sounds interesting and If we can ditch the PET tape it could be Great. I have not tried this yet, but will give it a go soon.

Electronics -

I used a scrap piece of Acrylic for the Electronics and PSU mounting, I wanted to make it all very super easy to access and tinker with on this machine.

The Acrylic plate slides into the vertical 20mm Slot sections that are also being used as reel mount for plastic filament reels.

A 240W 12V Power supply was mounted on the left.

With nice and easy Ring terminals for the connections.

One the left we have Mains 240V

Then the main +12V and GND connection to the RAMPS board

Heated bed source and Various other +12v signals for Lighting and fans.

RAMPS is simply mounted with M3screws and an ultra quiet, slow moving 80mm Fan for cooling the stepper motor drivers and Mosfets.

Using Stepsticks again and small heatsinks.

When you connect to screw-terminal connections (as on RAMPS) you should crimp the wires into wire ferules before inserting into the screw-terminals.

The smaller wires also crimped in are for an LED indicator on the outputs of Heaters 1 and 2 and also the Heated bed, quite handy to see what's energised. I need to make a little printed box for the LED indicators.

I have popped on to IRC a few times (as RichRap) It's really great, and opens up a whole new level of community spirit and help that the RepRap Forum does not convey. BUT it's a real time zapper, I would love to be on there more, but I'm going to have to finish some more projects first or they will never get done.

And I finally decided to get on Twitter, I going to blame Raspberry Pi :) for that, but I did eventually end up getting a RPi on order, so it was worth the early wake up, and Twitter looks another very interesting community for 3D printing.
I'm on Twitter as RichRap3D You can find me Here -

Mendel Bling Sold -

Many thanks to everyone that contacted me before, during and after the Bling eBay Auction, I spent the following week getting messages back to everyone, It really generated a lot of interest.

The Winner and new owner of Mendel Bling is James. Even though James had a long way to come, we had a great evening discussing 3D printing and I must have talked for at least a solid 3 hours straight. If I do that again, I'll video it as an intro tutorial.
James is planning to use his 3D printer to assist in one of his new businesses exploiting further work and research he did in his P.H.D.
James had some really good upgrades planned for Bling, I'm looking forward to see what he does with it and what it prints next. Almost everything on my Blog was printed on Bling, It did such a fantastic job for me printing most days for the last 7 months I'm a little sad to see it go.

James on the Left above and me on the Right

Thanks James, it was really great meeting you, I hope you enjoy using your new 3D printer !

Not a day goes by without something new going on in the 3D printing community, it's already a very interesting start to the year, I can't wait to see what comes next.

I'm really excited about my next Blog update, It's something I have been working on for a while now, finally it's fit for release, I'm sure some of you are really gong to like it.

Thanks for reading, let me know if you make a MendelMax or try out the Quick-Fit X-extruder concept, and I have many more extruder's and tools planned for this X carriage, I hope you find it useful too.

Great post as usual! Loving the fixing method you've come up with for the J head nozzles, I will be definitely moving over to your system rather than just securing the PEEK at the top! What Extruder block are you using (nozzle fixings)?

I find fixing it like this makes it nice and ridged and I have never had a leak or problem since using this method.

Not sure I get what you are asking about the extruder block? the J-heads are made with a single brass piece for Heating and Extrusion nozzle.The Nozzles are 0.5mm but you can get 0.35mm versions and I'm still using fire cement to fix the resistor and thermistor in place.

I was wondering which Extruder body you are using, and with which mounting option (or is it your own design)?As in I can tell your using a Wades extruder, is it Gregs version and with what mounting (i.e. obviously not the standard J Head mount) for attaching your PCB standoffs?

It's a slightly modified Greg's with a normal 16mm mount, and I believe standard ~30mm pitch M4 bolt spacing - the M4 stand-off's are screwed into the extruder body, the peek just gets pulled into the hole by the SS M4 bolts into the stand-off's, all nice and tight.I have included the Extruder model in the Quick-fit x carriage thing on Thingiverse if you want to take a look or print one. - http://www.thingiverse.com/download:62458

Excellent post - all sorts of cool stuff to think about. I was wondering, how well did it work to use the copper clad PCB attached to the standard MK2 Prusa PCB? Was the mirror you talked about using placed on top of that copper clad? I am starting a similar build that is a bit too large for the Prusa PCB. Your solution looks like something I might want to try - but not if you found that it didn't work well enough.

The copper clad board works very well, it was just what I had on hand that was about the right size, but it works a lot better than I expected, with the mirror-glass on top I can print in PLA over the entire surface of the glass.It heats up very quickly <3 mins.

I did have a cork sheet planned for underside insulation but in the end didn't install as it just didn't need it.

I think using the middle hole in the Prusa V2 heatbed really helps get heat into the copper clad board, I use a little kapton around the edges and measure temperature on the underside of the copper clad (copper side) around the edge.

Hi Rich,Thanks for an awesome post. I see that you are screwing the prusa PCB to your copper clad. How do you ensure that the screw or nut doesn't keep the glass from sitting flat for your print surface? (I am assuming that your glass is taped directly to the copper clad.) Is the copper clad just tapped and you cut the screw to size so it didn't stick out?

Also, I really like your idea of having a 9 pin connector for your extruder. Why did you need to have an extra cable for your heater? Isn't it 4 for the motor + 2 heater + 2 thermistor so you could easily fit it into just 1x9 pin connector?

I countersunk the heads into the copper clad PCB so they were flush for the mirror surface, they go through and clamp the Prusa heated bed tightly on the underside of the copper clad board.

The 9Way has a few extra connections for fans, and led lighting and I specifically didn't want the heater connections on a D-type as I plan to drive other things with a higher current.D-types can handle quite a few amps, so should be ok if it's just a ~20w hot-end.

I was curious as to where you get your plastic? I'm pretty new to 3d printing and I'm looking to get a variety of new colors in ABS or PLA. I was going to make an order from faberdashery but the shipping costs were way too high to the US. Any other suggestions?

Epic Post. I just thought I would give some feedback with the Mirror Printing surface - WOW!!!! I can't possible imagine anything that could more aggressively holds PLA and at a MUCH lower heated bed temperature.

Acting on your advice, I purchase some cheap $1 (0.61 lb) mirrored glass from our local Dollar Store. It is only 1.5mm thick. I had cracked a 2.5mm glass plate (my fault, I put a stress riser in it when I trimmed the corners to fit Prusa's MK1 board - the corner screws are always in the way), so I thought I would give it a go. Down the street at the Lowe's building center, they cut down glass plates for FREE (always affordable).

The cheap mirror is only 1.5mm thick and will visibly flex, it you try and remove parts off of it before they are competely cooled. At the 1.5mm, I have dialed down the heat to 40° C and I think it is still too high. Once the plate is totally at room temperature, the parts come off very clean, and very nicely.

Thank you very much for such a steady stream of great developments.

Next up, I am pocketing 10mm and 12mm aluminum plates to sandwich a Prusa MK1 Heated plate where the bottom is flush and has no protruding screws for the build surface. This will allow for better heat distribution for a 325mm x 325mm wide build plate that is exclusively heated with the Prusa MK1. I have insulated the back so most heat will be directed at the build surface. I will mount a much larger mirror to the flat alum build surface.

Great, I'm glad it's working for you too, I have shattered a few sheets by using aggressive cleaners, but now only use window cleaner on the mirror-glass. And if you ever get a piece that refuses to come off, just put a few drops of window cleaner on the glass-piece interface, capillary action will make it pop off straight away.

What is on the other end of the M3 screw that is part of the tensioner? I just printed out the quick fit carriage and I'm curious what the little white nub is. Is it printed, and is it threaded for the screw?

Do you mean on the Extruder Tentioner? they have captive M3 nuts in the body.

Or maybe you mean on the Quick-fit X carriage, that little white blob is a piece of Polymorph plastic, I have been meaning to design an end for this, just a cap with a captive nut to do the same job, but the polymorph one worked so well I didn't get around to doing it.I'm sure Nophead did one for his carriage on Mendel90, maybe we can borrow that one.

Just printed it. I found it on other belt tensioners on thingiverse: http://www.thingiverse.com/thing:26361A search for belt tensioner will yield many more, like this one: http://www.thingiverse.com/thing:16012

HelloI am well thanks. I have a medium sized MendelMax made with these printed t-nuts, they work very well.

My advice on MendelMax would be to make the X carriage wider (About +80mm) on the extrusions, that's basically what I have done on my middle sized version - this is so you can easily use dual extruders and still use the whole 200x200 build area, it also makes it easier to use.

Yes a version of it is up on Thingiverse - one of the first things I designed - http://www.thingiverse.com/thing:10767

But that was my original one, I made some changes and then had a HD crash after printing just a few of them, and lost the files, so at some point I'm going to re-make the design again. I only had one spare printed one, so I'll be soon!

Hi RichRap,i am a fan of your blog, it's great!I really love the j-head hack you did, you can even avoid a fan with that!It took a while to me to find the rail mount and unluckly that wasn't so cheap, but for anybody searching for it, the code is SHF12 for the 12mm and SHF16 for the 16mm, you can now easily surf the bay for it!RegardsPeppe

I am new to 3d printing and wonder what your opinion was on the final outcome of your builds of the the mendelmax as relating to size what was the ideal size normal, mini, big or massive in your opinion and why. Also could a dremel be mounted to your quick change baseThanks keep up the big workDave Marlow

I see that you sourced your aluminium extrusion from KJN in the UK as I am doing. The Mendelmax site says that along with the M5 to M6 tap change you also need to replace all the M5 screws with M4. Is this what you did on your build?